Micropillar array electrospray chip

Abstract

The invention relates to an electrospray ionization (ESI) device for forming a stream of ionized sample molecules. The device comprises a sample introduction zone for receiving a liquid-form sample, a tip for spraying the sample into aerosol or gaseous form, and a flow channel connecting the sample introduction zone and the tip. According to the invention, the flow channel comprises an array of transversely oriented microstructures adapted to passively transport the liquid-form sample introduced to the sample introduction zone to the tip by means of capillary forces. The invention concerns also a manufacturing method and applications of the ESI device, in particular mass spectrometry. The device can be used without external pumping of sample liquid.

1. An electrospray ionization device for forming a stream of ionized sample molecules, comprising:
 a sample introduction zone for receiving a liquid-form sample; 
 a tip for spraying the liquid-form sample into aerosol or gaseous form; and 
 a flow channel connecting the sample introduction zone and the tip, the flow channel comprising an array of transversely oriented first microstructures adapted to passively transport the liquid-form sample introduced in the sample introduction zone to the tip by means of capillary forces, 
 wherein the sample introduction zone and the flow channel are open from a side from which sample is introduced. 
 
     
     
       2. The device according to  claim 1 , wherein said first microstructures are micropillars protruding from a bottom surface of the flow channel. 
     
     
       3. The device according to  claim 2 , wherein said micropillars comprise substantially circular or elliptical cross-sections. 
     
     
       4. The device according to  claim 1 , wherein the first microstructures are arranged in rows shifted in one dimension in turns. 
     
     
       5. The device according to  claim 1 , wherein a cross-sectional diameter of at least one of the microstructures is 1-80 μm and a center-to-center distance between neighboring microstructures is 1-80 μm. 
     
     
       6. The device according to  claim 1 , wherein the flow channel is a depression in a substrate, the depth of the depression being 1-80 μm. 
     
     
       7. The device according to  claim 6 , wherein the flow channel in a vicinity of the tip tapers towards the tip as the depression approaches the tip. 
     
     
       8. The device according to  claim 1 , wherein the electrospray ionization device is fabricated on a glass, polymer, or silicon wafer. 
     
     
       9. The device according to  claim 1 , wherein the sample introduction zone comprises an array of second microstructures. 
     
     
       10. The device according to  claim 1 , wherein the sample introduction zone, the flow channel, and the tip lie on the same plane, the liquid-form sample is passively transported in a lateral direction along the same plane. 
     
     
       11. The device according to  claim 1 , wherein the sample introduction zone, the tip and the flow channel are in the form of a depression in a planar substrate, and the liquid-form sample is passively transported by the capillary forces in a plane parallel to the planar substrate. 
     
     
       12. The device according to  claim 1 , wherein a surface of the flow channel is provided with functional coating material selected from at least one of: hydrophilic coating material, hydrophobic, and non-polar coating material, the non-polar coating material comprising at least one of C18, C8, silica, and NH2. 
     
     
       13. The device according to  claim 1 , wherein a surface of the flow channel exhibits a contact angle for de-ionized water in a range of 1-45°. 
     
     
       14. The device according to  claim 1 , wherein at least one of the sample introduction zone and the flow channel comprises immobilized enzymes, microsomes, or other biological material. 
     
     
       15. A method for performing a mass spectrometric analysis, comprising:
 vaporizing a solution comprising a sample using an electrospray ionization device of  claim 1 ; 
 ionizing the vaporized solution to form gas phase ions using an electrospray ionization device of  claim 1 ; 
 separating the gas phase ions based on respective masses and charges of the gas phase ions; and 
 directing the separated gas phase ions to a detector. 
 
     
     
       16. The electrospray ionization device of  claim 13 , wherein the flow channel exhibits a contact angle for de-ionized water in the range of 10-35°. 
     
     
       17. The electrospray ionization device of  claim 13 , wherein the flow channel passively transports the liquid-form sample from the sample introduction zone to the tip without using voltage from a voltage source.